Cellulosic fibers can be easily and distinctly dyed with anionic dyes by direct dyeing processes. However generally speaking, textile materials dyed with anionic dyes by direct dyeing demonstrate very poor laundry fastness and wet fastness, and are therefore generally unsuitable for high grade fabrics. In order to improve the fastness (i.e., both laundry and wet fastness) of dyed materials, an aftertreatment chemical called a "dye fixing agent" is typically applied to the dyed material.
Dye fixing agents are of considerable interest in the art of textile coloring, and numerous dye fixing agents have been used and/or proposed in the past. One class of well known dye fixing agents employs formaldehyde as a starting material. For example, U.S. Pat. No. 3,490,859 to Soiron et al. discloses dye fixing agents based the condensation product of dicyandiamide and formaldehyde. Similarly, U.S. Pat. No. 3,995,996 to Pantke, et al., discloses dye fixing agents which include polycondensation products containing sulfonic acid groups of phenols and formaldehyde. However, the use of formaldehyde can be objectionable in the workplace and/or can require the installation of various apparatus in the workplace in order to eliminate or minimize undesirable effects believed to be associated therewith.
Cationic polycondensate dye fixing agents based on the reaction products of poly-quaternary ammonium salts, polyalkylene polyamines and dicyandiamide have also been used extensively as dye fixing agents. For example, U.S. Pat. No. 2,649,354 to Hemmi, et al. discloses dye fixing agents obtained by the condensation of an amine with a dicyandiamide. The reaction is carried out at a temperature on the order of between about 100.degree. C. and 210.degree. C. for several hours.
The dye fixative activity of cationic polycondensates is improved substantially by the incorporation of metal salts. Thus, Japanese Patent Publication Sho-45-2352 discloses improved dye fixing agents prepared by reacting a polyalkylene polyamine with a cyanamide or a cyanamide derivative, and a copper salt at a temperature above 100.degree. C. and a pH above 8. Japanese Laid Open Patent Publication Sho-48-39781 discloses further improved dye fixing agents prepared by reacting a polyalkylene polyamine with dicyandiamide and a Group II metal salt, e.g., ZnCl.sub.2, at a temperature of above about 150.degree. C. The metal salt is used in an amount of about 0.5 to 20 wt. percent, based on the two components. These dye fixing agents, in particular, have achieved substantial commercial success.
More recently, U.S. Pat. No. 4,764,585 to Heller, et al. proposes dye fixing agents prepared by reacting an amine and a cyanamide in the presence of a catalyst which can be a Group II metal or metal salt, or a heterocyclic nitrogen-containing organic base, at a temperature of between 60.degree. C. and 200.degree. C. When a metal or metal salt catalyst is used, it is used in an amount of 0.2 to 0.48 wt. percent, based on the polyamine and dicyandiamide.
Numerous modified cationic polycondensate dye fixatives, and modified processes for their preparation or purification have also been proposed. For example, U.S. Pat. No. 3,873,266 to Hofer, et al. discloses anionic dye fixing agents comprising polyalkylene polyamine-cyanamide condensation products prepared by reacting a polyalkylene polyamine and cyanamide at a temperature of between about 107.degree. C. and about 157.degree. C. U.S. Pat. No. 4,410,652 to Robinson, et al. discloses dye fixing agents including the reaction products of an amine with a cyanamide, dicyandiamide, guanidine or bisguanidine which is further reacted with an N-methylol resin precursor and heat cured in the presence of an ammonia salt catalyst. U.S. Pat. No. 4,439,203 to Runyon, et al. proposes dye fixing agents including the reaction products of a mono- or polyfunctional primary or secondary amine with cyanamide, dicyandiamide, guanidine or bisguanidine and either an epihalohydrin, formaldehyde or a dihydroxyalkyleneurea. Optionally, the product may be reacted with an N-methylol derivative of urea, melamine, guanamine, triazinone, urone, carbamate or acid amide. U.S. Pat. No. 4,439,208 to Moser, et al. discloses dye fixatives formed from (1) the reaction product of an amine with a cyanamide or dicyandiamide; (2) a quaternary polyalkylene polyamine; (3) formaldehyde, and optionally, (4) an N-methylol compound, which are reacted in the presence of a metal salt catalyst, at a temperature of between about 140.degree. C. to about 160.degree. C.
Recent years have seen dramatically increased efforts directed to preservation of the environment on a worldwide basis. Concurrently, substantial effort has been directed to minimizing use of various volatile chemicals, such as formaldehyde, in the workplace. As a result of these and other efforts, dye fixing agents containing and/or made from materials such as formaldehyde, metals and salts thereof, and other objectionable reagents, have become increasingly expensive to manufacture and use. However, the elimination of such materials substantially reduces effectiveness of the dye fixing agents, while the substitution of other highly reactive reagents for such materials, as has been proposed in the art, can also increase the costs associated with the raw materials and the manufacturing process. Moreover, many of the highly reactive reagents, as have been proposed for use in preparing modified cationic polycondensate dye fixatives, are also objectionable.